M. Namık Çağatay

Origin of the Sea of Marmara as Deduced from Neogene to Quaternary Paleogeographic Evolution of its Frame

The Sea of Marmara Basin (SMB) is connected to the fully marine Mediterranean by the Dardanelles strait and to the brackish Black Sea by the Thracian Bosporus. This linkage to two different marine realms with contrasting water chemistry has been a prime control on the sedimentary history of the SMB, which in turn was controlled by its tectonics. Isolation from any of these realms resulted in drastic changes in its paleoceanographic conditions and made it a part either of the global ocean system or of a brackish-marine environment, depending on the realm from which the connection was severed. The SMB represents the inundated part of the northwestern Anatolian graben system that resulted from the interaction between the North Anatolian fault (NAF) zone and the present N-S extensional tectonic regime of the Aegean. The geologic history of this basin began during the late Serravallian when the NAF was initiated. The first inundation of the basin coincided in both time and space with this initiation. The invad...

A 500,000‐year‐long sediment archive drilled in eastern Anatolia

Sedimentary archives host a wealth of information that can be used to reconstruct paleoclimate as well as the tectonic and volcanic histories of specific regions. Long and continuous archives from the oceans have been collected in thousands of locations by scientific ocean drilling programs over the past 40 years. In contrast, suitable continental archives are rare because terrestrial environments are generally nondepositional and/or subject to erosion. Lake sediments provide ideal drilling targets to overcome this limitation if suitable lakes at key locations have existed continuously for a long time.

Tectonic and sedimentary controls on widespread gas emissions in the Sea of Marmara: Results from systematic, shipborne multibeam echo sounder water column imaging

Understanding of the evolution of fluid-fault interactions during earthquake cycles is a challenge that acoustic gas emission studies can contribute. A survey of the Sea of Marmara using a shipborne, multibeam echo sounder, with water column records, provided an accurate spatial distribution of offshore seeps. Gas emissions are spatially controlled by a combination of factors, including fault and fracture networks in connection to the Main Marmara Fault system and inherited faults, the nature and thickness of sediments (e.g., occurrence of impermeable or gas-bearing sediments and landslides), and the connectivity between the seafloor and gas sources, particularly in relation to the Eocene Thrace Basin. The relationship between seepage and fault activity is not linear, as active faults do not necessarily conduct gas, and scarps corresponding to deactivated fault strands may continue to channel fluids. Within sedimentary basins, gas is not expelled at the seafloor unless faulting, deformation, or erosional processes affect the sediments. On topographic highs, gas flares occur along the main fault scarps but are also associated with sediment deformation. The occurrence of gas emissions appears to be correlated with the distribution of microseismicity. The relative absence of earthquake-induced ground shaking along parts of the Istanbul-Silivri and Princes Islands segments is likely the primary factor responsible for the comparative lack of gas emissions along these fault segments. The spatiotemporal distribution of gas seeps may thus provide a complementary way to constrain earthquake geohazards by focusing the study on some key fault segments, e.g., the northern part of the locked Princes Islands segment.

Sedimentary record of coseismic subsidence in Hersek coastal lagoon (Izmit Bay, Turkey) and the late Holocene activity of the North Anatolian Fault

This research was funded by the European Union in the framework of the REL.I.E.F. (Reliable Information on Earthquake Faulting) project (EVG1‐CT‐2002‐00069). Copyright @ 2011 American Geophysical Union.

Evidence of extensive carbonate mounds and sublacustrine channels in shallow waters of Lake Van, eastern Turkey, based on high-resolution chirp subbottom profiler and multibeam echosounder data

In Lake Van of eastern Turkey, the fourth largest soda lake in the world, high-resolution subbottom profiles and bathymetric data acquired in 2004 and 2012 revealed several hundreds of topographic mounds in shallow waters (<130 m) off the historical town of Adilcevaz in the northern lake sector. These structures are characterized by strong top reflections of transparent internal character, and are 10–300 m wide and 0.5–20 m high. Consistent with previous work, they are interpreted as carbonate mounds formed by precipitation from CO2-rich groundwater discharge into the highly alkaline lake. Their age remains to be determined but their alignment along faults suggests tectonic control on their growth. Several sublacustrine channel networks were observed on the eastern shelf of the lake, which connects with onshore rivers. The channels are up to 500 m wide and 20 m deep, and plausibly were formed by fluvial processes during the major lake level drop reported to have occurred by 14 ka in earlier publications. Erosion is common on the channel walls flanked by levees. The channels are presently inactive or abandoned. At a water depth of 100 m, they all merge into a single larger channel; this channel has a sinuous course initially trending southwestward and then northwestward at a water depth of 130 m. Numerous closely spaced small channels (~10–200 m wide, 1–10 m deep) are also seen on the eastern lacustrine shelf, interpreted as denditric and parallel channel systems formed during lake level fall terminating at ~14 ka. Bathymetric data provide evidence of numerous sublacustrine canyons on the western slope of the lake’s northern basin, most likely remnants of relict rivers formed during this lowstand.

From ESONET multidisciplinary scientific community to EMSO novel European research infrastructure for ocean observation

Environmental and climate changes are crucial challenges for sustainable living because of their significant impact on the Earth system and the important consequences for natural resources. Oceans have a primary role in these changes as they regulate heat flux, greenhouse gases and climate whilst harboring many different life forms and resources. Understanding processes in the marine environment is of paramount importance for any prediction of short-, intermediate- and long-term global change.

A Channeled Shelf Fan Initiated by Flooding of the Black Sea

High-resolution mapping and reflection profiling reveal a depositional fan on the Black Sea SW shelf fed from the Strait of Istanbul (Bosporus). The fan is constructed with an initial deposit of pebbles mixed with glacial and post-glacial shell debris. The pebbles are identical in their composition to quartzite and gabbro recovered in drill cores from the Bosporus Strait. Directly above the pebble layer are mollusks and foraminifera of Mediterranean provenance dated at 6.9 ka bp (uncorrected). Synchronicity between the onset of fan construction and arrival of Mediterranean fauna suggests an origin linked to the connection of the Black Sea’s lake with the global ocean. The volume of the chaotic interior of the fan is comparable in magnitude to the volume excavated from the floor of the Bosporus Strait. We propose that when the exterior ocean breached the sill of this inlet, it transformed into an outburst of saltwater that gained energy as it enlarged the inlet. Torrents stripped the glacial and post-glacial covering from its pathway and scattered entrained debris in sheets and mounds as far away as the edge of the shelf. Even in areas where the pre-existing cover survived, its eroded surface attests to the passage of flooding water.

Geochemistry of the Late Pleistocene-Holocene Sediments of the Black Sea: An Overview

The Black Sea sediments deposited during the last 30,000 yr consist of three units which can be traced over the deep Black Sea basin. The geochemical composition of these sediments reflects the paleogeographic, oceanographic and biological evolution of the basin during this period. The youngest unit, Unit 1, is a microlaminated coccolithophore mud that has been depositing since ∼3,000 yr BP, after the invasion of the Black Sea by coccolithophore Emiliania Huxleyi. This unit is enriched in Ca and Sr because of its high biogenic carbonate content and contains organic matter of mixed marine/terrestrial origin.

European multidisciplinary seafloor and water-column observatory (EMSO): Power and Internet to European waters

EMSO (The European Multidisciplinary Seafloor and water-column Observatory, www.emso-eu.org) is forging ahead through the next challenge in Earth-Ocean Science: How to co-ordinate ocean data acquisition, analysis and response across provincial, national, regional, and global scales. The coordination, analysis, and dissemination of ocean data continue to be a challenge across international boundaries. EMSO is a large-scale European Research Distributed Infrastructure (RI) of the ESFRI (European Strategy Forum on Research Infrastructures) roadmap, and is composed of fixed-point, seafloor and water-column observatories with the basic scientific objective of (near)-real-time, long-term monitoring of environmental processes across the geosphere, biosphere, and hydrosphere. It is geographically distributed in key sites of European waters, from the Arctic through the Atlantic and Mediterranean, to the Black Sea. EMSO ended its Preparatory Phase, EU Framework Programme 7 (FP7) funded project in 2012, and is now in the Interim phase transitioning to the formation of the legal entity for managing the distributed infrastructure: the EMSO European Research Infrastructure Consortium (hereinafter EMSO-ERIC). A phased implementation will characterize EMSO site extension, construction and operation. Countries currently participating in EMSO are: Italy, France, Ireland, Spain, Greece, United Kingdom, Portugal, Romania, Norway, Sweden, Turkey, Germany, and the Netherlands. The user community is open to all, and will be coordinated through an association called ESONET-Vi (European Seafloor Observatory NETwork - The Vision), following on the extensive scientific community planning contributions of the ESONET-NoE FP6 project. The most striking characteristic of observatory design is its ability to address interdisciplinary objectives simultaneously across temporal and spatial scales. Data are collected from the surface ocean through the water column, the benthos, and the sub-seafloor. Depending on the application, in situ infrastructures can either be attached to a cable, which provides power and enables data transfer, or operate as independent stand-alone benthic and moored instruments. Data, in both cases, can be transmitted realtime through either fibre optic cables, or through cable and acoustic networks that are connected to satellite-linked buoys. EMSO provides power, communications, sensors, and data infrastructure for continuous, high resolution, (near)-real-time, interactive ocean observations across a truly multi- and interdisciplinary range of research areas including biology, geology, chemistry, physics, engineering, and computer science; from polar to tropical environments, down to the abyss. Such coordinated data allow us to pose multivariate questions in space and time, rather than focusing on single data streams. Continuous data are required to document episodic events, such as earthquakes, submarine slides, tsunamis, benthic storms, biodiversity changes, pollution, and gas hydrate release. Longer term time series are relevant for monitoring global change. EMSO not only brings together countries and disciplines, but allows the pooling of resources and coordination to assemble harmonised data into a comprehensive regional ocean picture which it will then make available to researchers and stakeholders worldwide on an open and interoperable access basis.

The MARDEP project: The Sea of Marmara observatory infrastructure for multidisciplinary earthquake and environmental research and monitoring

The Sea of Marmara (SoM), located on the North Anatolian Fault, is under the risks of large earthquakes, submarine landslides and tsunamis. It is also under a serious environmental risk. The SoM is also interesting in terms of its oceanographic setting between the Mediterranean and the Black Sea, being characterized by a two-layer flow system. The study of the ecosystems, especially those located along the active faults where methane and hydrogen sulphide are emitted, is an interesting research topic. Because of all its interesting features, the SoM has been selected as an important site for European Seafloor Observatory Network of Excellence (ESONET NoE) and European Multidisciplinary Seafloor Observatory Infrastructure (EMSO) projects. The MARDEP observatory infrastructure has been developed under ESONET NoE project using the ESONET label. It is designed as three fixed modular units located on different fault segments, each connected to a shore station with a buried cable. The observatory will therefore be with real-time data transmission and powered from the shore. The observation sites were selected after detailed site surveys. The design involves nodes and junction boxes and other standards (e.g., Ethernet, serial interface, clock synchronization), adaptable to new developments. The sensor package includes seismometer, piezometer, bubble meter (BOB), methane, oceanographic, and other environmental measuring devices. The proposal will be submitted for funding in 2011. When funded, the observatory will become operational within three years as an EMSO regional department.